We had an odd mix of a lot of these rules..
Parents were born in 41 and 43...but fairly old when they had us (80/81)
No drinking with your meal or immediately before - you'd fill up on drink and not eat your food. This wasn't fabulous for me as I had/have a sliding hiatus hernia that was undiagnosed (and wouldn't be for another 38 years!) and really struggled to swallow anything remotely dry or claggy!
Eat what was on the plate or it would be served to you again next meal/or you weren't allowed to leave the table/didn't get any afters (this alternated but one of these always applied). See above - boy did I suffer!
Had to say 'please may I be excused from the table' before leaving the table. Unless we had guests in which case we weren't to ask we had to wait until we were excused. This led to some meals where my sister would fall asleep face down in her food if the guests were particularly interesting/wine flowing/late hour. I don't think I ever did but I've always been a night owl!
No eating whilst out in the street unless sat on a bench - eating whilst climbing a mountain, walking the hills or down a cave - A-OK.
Chocolate and sweets were either not a thing we were allowed at all OR if we were really good, Saturdays were the day. That promise could be removed for any infraction of the rules at any point during the week so effectively, the former applied most of the time.
Heating on from November to March, only if everyone was home, only if it was cold even if you had on several jumpers.
No sitting under a blanket on the sofa!
No eating in the living room/whilst watching TV/outside - except at weekends my father delighted in making himself bacon sandwiches and eating them outside in the garden or in winter, in front of the TV! But we weren't to do same (to be fair, her rule, not his, he really couldn't have cared less!)
Sundays were frankly, frigging horrible - doing chores for mother, which mostly involved being shouted at for not 'using my initiative' *(i now realise.. actually, mind-reading what she would want before she asked, beyond my skills at the ages of 4 upward). There was nothing on TV in the time frame we were permitted to watch it, we didn't go anywhere if we were at home (if we were away we'd be journeying home so that meant car sickness!), shops were all shut... misery!
Baths were shared, 3" deep max - initially the two of us shared a bath, then had our own bath but sharing the same water. Occasionally one (or both when v small) we'd get in the bath with my dad (IF he was in the mood to entertain this) which was A HUGE treat because he'd have the bathwater near overflowing the bath, he'd block the overflow and for a toddler that meant HOT water up to your NECK... omg the joy!!!
Baths were once a week, at the weekend at some point. Strip wash at your sink in your room the rest of the time (yes all the bedrooms had a sink).
ITV we did not watch. I don't recall why, probably avoiding us seeing advertising. BBC was the thing, but no Grange Hill (would turn me into a delinquent clutches pearls. If she'd ever clapped eyes on Byker Grove that would also have been banned, but she had no clue.
Most of it was about saving money tbh - some of it was about not looking common in front of people. Some of it was my mother being batshit.